This invention relates to an endoscope provided with an ultrasonic oscillation unit having a plane for emitting and receiving an ultrasonic wave so as to perform an ultrasonic diagnosis.
A conventional endoscope, shown in FIG. 1, capable of performing an ultrasonic diagnosis comprises, for example, an electron scanning type ultrasonic oscillator 5 disposed at the distal end 2 of the insertion portion 1, i.e., the portion inserted into the body cavity. The oscillator comprises a plane for emitting and receiving an ultrasonic wave, said plane being located on the same side as a view window 3 and an illumination window 4 provided on the distal end 2 of the endoscope. For performing an ultrasonic diagnosis, the distal end 2 is bent while a body cavity wall 6 is being observed through the view window 3 so as to bring the ultrasonic wave emitting-receiving plane of the ultrasonic oscillator 5 into direct contact with the desired portion of the body cavity wall 6.
In the prior art endoscope of this type, however, the view window 3 is also moved together with the ultrasonic oscillator 5. Thus, it is impossible to secure a sufficient view field, rendering it difficult to bring the wave emitting-receiving plane of the oscillator 5 accurately to the desired position. Also, the manual operation for bringing the wave emitting-receiving plane into direct contact with the desired portion of the body cavity wall 6 requires a skill of high level; in general, it is difficult to achieve a satisfactory contact in question. Further, the illumination window 4 is also moved together with the view window 3, quite naturally. Thus, if light of high intensity is used for illumination purposes, the body cavity wall 6 tends to be burned. In order to avoid a accident, it is necessary to use a weak illumination light, making the manual operation of the endoscope more difficult.
An object of this invention is to provide an endoscope easy to operate and permitting the ultrasonic wave emitting-receiving plane of an ultrasonic oscillator to be brought accurately to the desired position.